The reactions pp→pΛK+ and pp→pΣ0K+ near their thresholds

The reactions pp→pΛK+ and pp→pΣ0K+ are studied near their thresholds. The strangeness production process is described by the π- and K exchange mechanisms. Effects from the final state interaction in the hyperon-nucleon system are taken into account rigorously. The Λ production turns out to be dominated by K exchange whereas K- as well as π exchange play an important role for the Σ0 case. It is shown that the experimentally observed strong suppression of Σ0 production compared to Λ production at the same excess energy can be explained by a destructive interference between π and K exchange in the reaction pp→pΣ0K+. Implications of such an interference on the reaction pp→nΣ+K+ are pointed out.